Step drill grinder



Aug. 14, 1951 R. T. MURRAY 2,564,496

v STEP DRILL GRINDER Filed July 12, 1948 7 Sheets-Sheet ENTOR. Pqsse/l 7. Murray Aug. 14, 1951 R. T. MURRAY STEP DRILL GRINDER 7 Sheets-Sheet 2 Filed July 12, 1948 Z 0m T W W WM/ W m H II 6 N mHrnH wY 9 D m MW WW QQ @Q rk QN .Q m o y a Q g g Q Q o g Q\\ N w v M o o O @Q g. g 5 s g 3 Q R w i g L twill x Q3 Q3 ATTORNEYS Allg- 9 R. T. MURRAY STEP DRILL GRINDER Filed July 12, 1948 7 Sheet-Sheet 5 N v E N TO R Aussefl Z'Murrag ATTORNEYS Aug. 14, 1951 v R. T. MURRAY STEP DRILL GRINDER '7 Sheets-Sheet 4 Filed July 12, 1948 illlllllllllllllllllllllllll I NVENTOR Russell TMur/a ATTORNEYS 14, 1951 R. T. MURRAY STEP DRILL GRINDER 7 Sheets- Sheet 5 Filed July 12, 1948 I NV E N To R Russe/ T Murray ATTORNEYS Aug. 14, 1951 R. T. MURRAY STEP DRILL GRINDER 7 Sheets-Sheet 7 Filed July 12, 1948 INVENTOR Russe/l TMur/zg BY 6% M SW Q & MN m miflhh wt J ATTORNEY Patented Aug. 14, 1951 UNITED STATES PATENT OFFICE STEP DRILL GRINDER Riussell T. Murray, Rockport, Ind., assignor, by

mnesne assignments, to Grove Regulator Company, a corporation of California Application July 12, 1948, Serial No. 38,269

3 Claims. (Cl. 51-219) chinery for the manufacture and reconditioningof twist drills of the step type (i. e., drills having cuttin edges on two or more diameters). Because of the difficulties and extra machining operations required such drills sell at a premium price. Most shops or manufacturing establishments making use of step drills have no adequate facilities for their sharpening or reconditioning. As a result the drill costs involved in certain machining operations may amount to a considerable factor, and may preclude or minimize their use in many operations in which they could be used to great advantage, if adequate means could be provided for their economical reconditioning.

Less expensive machines for grinding step drills have been available for shop use, but they have been relatively impractical and uneconomical. Because of the inconvenience with which the various operations can be carried out on the machines, the cost to the average shop has been excessive, and great skill must be exercised by the operator of the machine in: order to secure accurate results. In particular it has not been possible with such machines to carry out the various grinding operations without time consuming readjustment or resetting of the machine.

It is an object of the present invention to provide a machine for the grinding of step drills which will enable the grinding operations to be carried out with great facility compared to prior available machines.

A further object of the invention is to provide a machine of the above character which will enable one to carry out a complete sequence of required grinding operations without a resetting of the machine.

Another object of the invention is to provide a machine of the above character which can be readily adjusted for the particular skew of the drill, and which enables the same adjustment to be used in the grinding of one or more steps.

Another object of the invention is to provide a machine of the above character, which is provided with means whereby after grinding a length of the drill stock to proper length, the same can be operated to turn and advance the drill against the grinding wheel to produce the desired cutting edges and clearance for the step shoulder of the drill.

x and is attached to a shaft 30 which extends from Additional objects of the invention will appear from the following description in which the preferred embodiment of the invention has been set forth in detail in conjunction with the accompanying drawing.

Referring to the drawing:

Figure 1 is a side elevational view illustrating a grinding machine incorporating the present invention.

Figure 2 is a plan view of the machine shown in Figure 1.

Figure 3 is a side elevational view of a part of the machine, namely the drill supporting head.

Figure 4 is a plan viewof the drill supporting,

head as illustrated in Figure 3.

Figure 5 is a cross-sectional view taken along the line 55 of Figure 4.

Figure 6 is a cross-sectionalview taken along the line 6-6 of Figure 4.

Figure '7 is a cross-sectional view taken along the line 'I'I of Figure 4.

Figure 8 is a sectional detail showing the hand operated feed screw.

Figure 9 is a cross-sectional view taken along the line 99 of Figure 8. v

Figure 10 is an end view of a step type drill.

The machine as illustrated in the drawing consists generally of a supporting frame I0 providing horizontal ways II and upon which the carriage I2 is slidably mounted. This carriage serves to mount the drill supportin head I3, and its position along the length of the machine can be adjusted by a conventional feed screw and hand wheel I4. The head I3 is adapted to receive the drill to be ground, and in the various operations of the machine the drill is advanced against the grind wheel I5 of the grinding head I6.

whereby the plate I9 can be moved alon the ways I! and I8. Thus a feed screw 2| is mounted within the carriage I2, and is engaged by nut 22,

which in turn is secured to the plate I9. A hand wheel 23 is positioned at the frontof the machine,

the carriage. This shaft is operatively connected with the feed screw 2I through the bevel gears 24 and 24a. Thus upon turning the hand wheel- Plate I9 serves to mount a supporting bracket 26, which inturn carries the spindle enclosing housing 21. I This housing can be conveniently An adjustable stop- 2,564,496 ET i The forward part of the spindle 28 is. formed.

to provide the tubular portion 28a, and this portion is rotatably fitted in a bushing 29, which in turn is attached to the adjacent end portion of the housing part 21b. A suitable thrust bearing assembly 3| is interposed between housing part 21b and the sleeve portion 28a; to take thrust forces which may be applied to the spindle tending to urge the same to thegright as viewed in'Figure- I'. Withinthe sleeve portion 28a. of the spindle there isa socket sleeve 32, which is bored to:

receive the shank 33 of a drill. Socket sleeve 32 isprovided with diametrically opposedkeys 34, slidably accommodated in the grooves 36 formed in the spindle portion 28a. Thus socketsleeve 32 mav'movealimited amount longitudinally of the spindle, but is always keyed to the spindle for concurrent rotation with the same.

At its rear. end the. socketsleeve 32 is shown provided with a recess 31 for receiving the flattenediend portion 380i the drill shank. Portion 38 is adapted, to abut the .pin. 39., which is received in a bore 4.! provided in the spindle. An opening 42 is provided in the. spindle whereby a Wedge canzbe inserted in. this opening-,.for driving pin, 39 against the shank of the drill, to thereby positively-eject the same.

A cup-shaped shell orbarrel 44 is rotatably fitted upon the adjacent endof the spindle housing 21b, and its end wall 46..has. an opening to .accommodatethesocket sleeve .32'. The projecting end of the socket sleeve is threaded to receive the locking nut 41. A compression spring. 48. is disposed between the socket sleeve 32 and the spindle part. 2811, and its one. end iseseated upon the end of the bushing 49, which is looked as. by screws 5| to the spindle part 28a. The other end of thespring is seated against an annular shoulder formed bythe shoulder part 52, which. isattached to the adjacent endportion of the socket sleeve'32. By loosening nut 41 it is possible to unlock thespindle with respect to the cup-shaped shell 44', thus permitting the latter to be turned toa different angular position relative to the spindle and to the drill carried by the same.

It will be noted that all of the parts just. de-.

isadapted to be frictionally engaged or disen gaged with respect to the beveled shoulder 51,

formed on the spindle part 28b. Adjacent the right hand end of the sleeve 54 as-viewed' in Fig-;

ure '7, the spindle is provided with diametrically extending openings 58; which accommodate the rev bar 59. The end portionsof key'59 abut the djacent end of the sleeve 54', whereby when the riage l 2. The other end of the cam-arm -I.92-:.car:-.- ries a bushing I06 and a lock bolt I01. Therbushe- 4 key is urged to the left as viewed in Figure '7, sleeve 54 is urged in a direction to force the clutch surfaces 56 and 51 into driving engagement.

The interior of the housing part 21a forms a cylinder bore 61,,whichis t'fitted'with a pneumatic piston 62. ..This piston has: threaded engagement 63 with the spindle portion 281), wherebyair pressure applied to the space 64 at one side of the piston 62 serves to urge the piston together with the entire spindle toward the left. A pipe '665- connects with the space 64, and leads to a source of air under pressure, through a suitable operator controlled valve.

The spindle part 28a is journaled within a bushing 68, which in turn is fitted within the body part 21a. Bushing 68 also serves to journal the hub of a sheave 69,}Iand the sheave is normally held assembled relation on the machine by. a-pin lil, which extends: into a groove lfi...

The hub. of sheave 69 also has a retractable drive pin 13, the inner end of which is. adapted to ena gage in a groove 14 formed in the spindlel'part 28c. Suitable drive means such as a V-belt 15 serves to operatively connect the sheave 69 with a sheave 76', which in turn is driven bythe electric motor 11:. This motorincorporates a speed re-- duction gearing to drive sheave 1-6 .at a proper speed.

The rear'end of the spindleqpart 280 carries a disc 18, which cooperates with movement limiting means to be presently described. Extending axially through the spindle part 28,0 there is a rod- 19, oneend of which abuts the key 59 and the other end of which can be engaged. by the handoperated screw 8|. Thus by turning, the screw 84- rod 19 can apply suflicient thrust to the key 59-to. force the frictional clutch. surfaces 5,6- and 5:1 to.-

gether. v

The movement limiting means cooperating,

with thedisc TBincIud'esthe: stop 1,ug-82,which.is

slidably carried by themounting bracketi 8.3.. By. 7 meansnof a threaded screw/814 which. is threaded:

into the. bracket 83, the. stoplug 82; can bead-s justed to the left or. tortheright as:viewed .in-Figure ".1. A small roller 85% is carried by lug and is adapted: to. be engaged by. the disof'l8 to limit movement/of. the. spindle to the left.

The precision turning means for the spindle includes a sheave. 88; which iszloosely mounted: upon sleeve 54, and splinedxthereto by key 8.9; Below the sheavey8'8 thereis .a similar. sheave. 91'

which is fixed on the hub. 92., the latter beingii'n turn journaled upon the shaft-.93. Suitable end:

steel belts 9 9 (Figures G and '7 operate withinv theshallow grooves 94 and 96; which. are' formed on. the peripheries of the sheaves 88 and.i9;l1. 1 These.

belts are anchored to the peripheries of the sheaves M ami 91 bytheattachingmeanswa. and

96b. Instead ofusingsheaves together'withsuch. metal belts, one can employ directly meshinggearsof proper accuracy.

The extending end portion 9'!" of the hub- 9-2 is formed'as apinion, the'teet-h-of which engage the teeth of a gearrack 98-. This rack is guided for ing and lock bolt assembly. extend through an are: cuate slot I08 in the topwall IBI J-of the carriage; I2. By means of a suitable wrench orothertool. applied to the lock bolt I01, the corresponding end. of the cam arm I02 can beadjustedto a. desired position, to thereby position the angle of the cam arm relative to the longitudinal axis of the machine. The cam arm is provided with ,a. linear cam groove I09, which servesto accommo-. date the cam block I00. Assuming that the cam arm I02 is set at a given angle with respect tothe longitudinal axis of the machine (Figure 4), it. will be evident that when the entire drill supporting head of the machineis moved tothe left ;or to the right, that is toward or away from the grinding head, cam block I is caused to slide along the cam groove I09, thus moving the :gear

rack 98 laterally of the machine to impart rotary movement to the spindle through pinion 91, and

sheaves 9| and 83. It may be explained atthisf point that the camarm I02-can be set by the operator in accordance with the skew. of a par- I ticular drill to be ground. Therefore for grinding operations to relieve theland of the drill it is possible to advance the drill stock against the grinding wheel with rotary movement corre-.

sponding to skew of the drill. I

In order to facilitate thegrinding of theIcut-Q ting edges between the different drill diameters; means is provided for enabling rotary motion of the drill together with a predetermined amount of advancement of the drill and spindle, without however moving the entire head assembly or the sheaves 88 and 9|. Thus the forward barrel 44 is provided with a flange III, which is provided with spaced threaded openings to receive the-cam pins H2 and II3, located 180 apart. Two pins. are provided on the assumption that a, double fluted twist drill is to be ground. Should asingle fluted twist drill be ground then a single pin will sufiice, or if a four fluted drill is being ground, then four pins must be provided located 90.apart, Pins H2 and H3 are adapted to engage the for: ward edge of an arcuate cam bar I I4. This bar is pivotally attached by screw I IE to an adjustable mounting pad II! which in turn is seated upon the housing part 211). A pOilfiterarmv ll8 is'at tached to and extends rearwardly from the cam bar I I4. It is provided with an enlarged opening to accommodate the clam screw I2 I Upon loosening the screw IZI the pointer arm II8 can be moved between limiting positions, as may: be indicated by graduations I22. A block I23 is attached to the inner end of screw I2I,- and fits within the annular groove I24 provided in the spindle 28. A spacer I25 is also carried by screw I21 and is provided with a flat key-like portion I26. This portion fits snugly with-the milled 1 housing slot I27 and theslotlzain-pad -II'I., Assuming that the arcuate cam bar H4: isdisposed at an angle such as illustrated for example. in Figure 4, and assuming that the spindle is disengaged (by release of the clutch) 'fromdriv-u ing relation with the sheaves 88 and 9|, manual turning of the barrel 44 to bring one of the pins I I2, I I3 into operative engagement with the edge of cam bar I I4, causes the barrel 44 together with the drill socket 32 to be advanced forwardlyas; it is rotated, such forward movement (being, accommodated by sliding of the socket sleeve 32 within the spindle part 28a, and being against the compression of spring 48. When the barrel 44 has been turned sufficiently far'to disengage a particular pin H2, H3 from the cam bar -I I,4,-;; hsnethe ba together w ththe sqcket sleeve.

In certain grinding operations the cam bar I I4 must be moved to an out of the way position. This can be done by loosening screw I2I and then sliding mounting pad I I! a limited distance away from the barrel.

.The grinding head l6 for the machine is. preferably adjustable whereby the grind wheel.

I5 may be raised or lowered, adjusted laterally, and alsoadjusted with respect to the angle of its axis relative to the axis of the spindle. As representative of such an adjustable holder for the grind wheel, the wheel is shown mounted upon .a shaft carried by the journal head I29, and driven by an electric or pneumatic motor I30. Journal I29 is a part of a journal mounting I 3I which is carried by the plate I32 in such a manner as to enable angular adjustment about a vertical axis. Plate I32 slidably engages ways upon a plate I33, and hand wheel I34 in conjunction with conventional screw means, enables adjustment of the grinding wheel longitudinally of the machine.

I37, which extends vertically and telescopes into the base II] of the machine. A lock lever I39 is provided for locking the grinding head after its adjustment to a desired level. A suitable feed screw operative by the hand wheel I4I, enables adjustment of the wheel in a direction laterally of the axis of the spindle, and as previously explained turning of hand wheel I34 serves to move the wheel in a directionlongitudinally of the spindle axis. Hand wheel I40 operates through a conventional feed screw means foi raising or lowering the entire head.

It is desirable to provide a suitable dressing tool and a holder for the same in order to enable accurate dressing of the grind wheel. For this purpose there is shown a grind wheel dressing tool I42, mounted upon a suitable adjustable holder I I43. The part I41 of the holder, which serves to mount the dressing tool I42, is slidably engaged with an adjacent part I48 (Figure 2) which in turn is adjustably clamped to the part I49. The adjustable engagement between parts. I48, I49 enables angular adjustment about a horizontal axis extending transverse to the machine, and the parts can be clamped in a given angular position by hand wheel I50. Hand wheel I5I enables sliding adjustment between parts I41 and M8,

whereby when the parts are in the position shown in Figure 2, turning of hand wheel I5Iv serves to move the dressing tool longitudinally of the machine. Normally the dressing tool is offset to one side of the axis of the spindle. The grind wheel can be shifted to a position directly over the pending stud IGI, which extendsthrough the bracket I56 and is provided with a retaining nut I62. Ring I 59 is fitted with a journalbushing-I 63,

which in turn serves to journal an inner assembly I64 which is attached to the drill stock I651 The Plate I33 slidably engages laterally: extending ways formed on the plate I36 and the latter member is a part of a supporting standard.

accesses assembly Hi4; consists .in1thi'sinstancemfthe split. collet: Hi6 together with. the interfitting clamping: rings IBT. and IE8. Clamping; ring I61. has threaded engagement I69. withthe clamping ring I68, andalso hasbeveled. shoulders Ill and. 112- which engage complementary beveledshoulders formedi onrthe collet I66. Ring I68. urges the bevel of washer ll3aagainstabeveledend. of the coll'etilEG whereby when the: two clamping. rings I61 and IE8 are turned in opposite directions by application of suitable tools, forces-are applied to the collet. |66- to.contract the same to tightly gripthe drillstock 165'. A characteristic of this steady rest is that although it prevents lateral movement of the drill; the drill is free to turn andto move longitudinally of its axis.

Operation of my machine'can be described as follows: Assuming first that it is desired to form a step drill from a standardsingle diameter drill, the shank of the drill is seated in the socketsleeve- 32 and-the'steady rest is applied to the-projecting stock I65 of thedrill in the manner previously described. Thetwistdrill stock is presumably formed to a single diameter and ground at its end to form two accurate cutting bits; The grind wheel isfirst adjusted to a position with its axis in a vertical-plane coincident with theaxis of the drill. Pipe 66 is connected to a source of air under pressure whereby the spindle is alwaysurged'towardthe left as viewed-in Figure l. The positioning of thecarriage l2 with respect to-the base I0, and the positioning of the base plate IS with respect to the carriage I2, is such that when the plate 19- is' near the right hand limit of its movement relative-to the carriage-(Figure l) andwith the spindle-in the position shown in Figure '7, the end of the drill stock is in proximity with the grinding wheel. Assumingthat' a single step drill is to be ground, the first operation is to rough grind the end of the drill stock to the smaller diameter. Thus the'sheave 59 is'operatively connected to the spindle by releasing the drive pin 73 to engage groove 14, and the electric motor 1'] is set in operation. The gap between the stop disc- 'Hland the stop roller 86' is set to correspond to the length of the smaller-diameter to be ground. The spindle carrying base I9 is: now moved-t theleft to advance the stock against the grinding wheel, assuming, of 'course, that thegrinding wheel is properly adjustedto take a cut; When a out has been taken corresponding to the length of the smaller drill diameter being ground; disc"18: comes into engagement with the stoproller 86, thuspreventing further advancement of the stock against the grinding wheel. The op-- erator then returns the spindle carrying base I9 for another out. One continues inthismanne-r until one has arrived at substantially the diam eter'desired. The. drill stock will at'this time appear substantially as shownin Figure 3.1

In place of using a square cornered grind wheel as; indicatedv in theabove explanation, for the preliminary rough. grinding operation, it is possible to use a grind: wheel having abeveledied'ge la, substantially as shown inFigurel'. When; the drill stockuis operated upon with such a. beveled grind wheel, the resultis shown in'outline in Figure 10. Itwill be noted that the shoulder between the larger and smallerdiameters of-th'e stock is on a bevel, instead of. being in a; plane at right angles to the axis of the stock, as in: Figure 3.

The operator now resets the positionbf the grind: wheelwhereby. it is attan angle-tea vertical. plane coincident with'thespindle. axis, the'angle:

8 corresponding: to: the: angle of: clearance. desired. in sharpening the lips. of. the. shoulder. After. sets tingthe axis 0f. the wheelat this angle, the wheel is shifted t aposition directly overlying: the: dressing tool, and; the dressing tool is then traversed across the face of the wheel" in: order that the. wheel: base ma cut accurately on the smaller diameter, while at such am angle. A't thesame' time the edge of the wheel may be dressed: to provide the desired bevel, as? suming that this bevel has not already beem present.

With. the grind wheel in operation the oper-- atormaynow takeone or more finishing cuts: as desired on the smaller diameter. Then one proceeds to grindthe shoulder between the different' diameters, to provide the desired cutting edges with desired clearance. To carry out this phase of the grinding screw I2! is loosened and the pad H1 together with finger H8, is shifted to an operative position, with the finger H8 set. at an angle depending upon the clearance desired; Screw I2! is then tightened to clamp theparts together; Cam bar H4 will then occupy 5a osition substantially as shown in Figure 4-;

. for the shoulder grinding operation. The oper-- ator then manually turns the barrel 44 in a clock-- wise-direction as viewed from the shank end of the drill, thereby causing'the drill stock to rotate and to simultaneously be advanced against thebevel of thegrind wheel, at a rate determined by the angular positioning of the cam bar H4. When the engaged cam pin has passed the cam bar I I4, thedrill stock is rapidly retracted. Then the barrel 44 is turned sufficiently far to bring the-second cam pin into engagement with bar' I 14-. Further turningof the barrel then advances thedrill' stock against the grind wheel togrind" the second cutting edge.

Instead of turning the barrel by hand one" mayreleasethe pin 13 for connecting motor 11'. The operator then turns the hand wheel 23 slowly-- to the right and then to the left, while the drill stock is in slow continuous rotation and is being advanced and retracted by the cam bar H4.

Following the shoulder grinding operations de-' scribed above, one may proceed to finish grinding-- the lands of the smaller diameter of the drill stock (assuming such operation has not been carried out before the shoulder grinding operation). This can be carried'out by a succession of grind ing cuts across each land of the drill on the smaller diameter, while rotary and advancingmovement is being-imparted to the stock, in the manner previously described.

It is-also possible by use of the machine toprovide proper relief for the lands as indicated at; I14 inFigure 10. In carrying out this operation cam bar I02 is set-to aposition corresponding to the skew of the drill, pin 73 is disengaged, and

:the spindle rotated by hand. This results in simultaneus advancement and turning of the drill stock whereby when the grind wheel is properly' adjusted,- the lands can be relieved to theextent desired.

I claim:

1. In astep type drill grinder, a spindle, a-= drill holder'in alignment with the spindle and" splinedindriving engagement with the same; spring meansfor urgingthe holder toward re-- tracted position relative to the spindle, means for"- advancing the spindle and holder toward a grinding zone and for simultaneously rotating the spindle and holder at a rate corresponding to the skew of the drill, a releasable clutch in said last named rotating means, manual means for rotation of the holder when said clutch is released, and cam means for independently advancing the holder at a rate corresponding to the cutting edge clearance in response to manual rotation of the same.

2. In a step drill grinder, a machine base, the base being provided with a guideway, a support carried by the guideway for movement in opposite directions, means carried by the base for movin the support along said guideway, a spindle journaled to the support, a drill holder carried by the spindle, a cam bar having one end of the same journaled to the base, said cam bar being ad- Justable between limiting positions, in one of said limiting positions the cam bar being parallel to the axis of the spindle and in the other limiting position the bar being at an angle to said axis, and drive means serving to operatively connect said cam bar to said spindle, said drive means comprising a sheave carried by the spindle, releasable clutch means for forming a drive connection between said sheave member and said spindle, a second sheave member mounted below the first member and on an axis parallel to the same, drive elements serving to operatively connect said sheave members, a pinion carried by said second named sheave member, a gear rack slidably mounted in said support and disposed substantially at right angles to the axis of the spindle, said gear rack having its teeth operatively engaging the teeth of the pinion, and means forming an operative engagement between said rack and said cam bar.

3. In a step drill grinder, a support, a spindle journaled upon the support, a barrel carried by one end of the spindle, a drill shank holding socket carried by the barrel, means forming a spline drive connection between the barrel and the spindle, whereby the barrel may move longitudinally of the spindle between limiting positions, spring means for normally urging the barrel toward retracted limiting position relative to the spindle, and adjustable cam means for causing projecting and retraction of the barrel relative to the spindle upon rotation of the barrel.

RUSSELL T. MURRAY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,212,855 Chittenden Aug. 27, 1940 2,452,703 Umbdenstock Nov. 2, 1948 

